Was tightening the hood nut, and then crunch - the hood casing cracked ! The
crack forms about a 1 inch circle around the nut. Next time I have a chance
I'll try to get a photo of this uploaded. Nothing unusual was occurring - was
applying just a normal amount of force.

Very similar thing happened to the hood on my 300L II. Canon replaced it under
warrantee. For the 500L II, they are saying it's not covered (even though the lens
is well within the 1 year warrantee).

Anyone else have this happen on the 500II ? Any thoughts on dealing with
Canon service ?

Maybe I guess,.. but hard to imagine what I could be doing wrong. Just tightened the nut, until it started to get snug. Didn't keep tightening until it was tough to turn. Have had no problems with any other hood other than the 300II (I've had experience with many of them, including the old 300, old 500, and old 800).

The hood is held by the groove of the lens. There is really no need to tighten the nut with force at all. I normally just turn it until I feel the first resistance. So far, not a single time has any hood popped out by doing just that. To answer your question, no, it hasn't happened to me with any of my superteles in the last 10 years and not with the Mark IIs either more recently. Knock 3X.

As Joshua wrote, the locking nut should be fingertip tightened lightly.....not so much to positively secure the hood, but to prevent the nut from undoing itself.
However, I am having a difficulty accepting that the hoods would crack as a result of application of reasonable amount of locknut tightening. However, one never knows....perhaps there is a material weakness in the MkII hoods. They sure made them much lighter, I hope that hasn't resulted in undue fragility.

Thx for the replies folks. Sounds like I may tighten the nut a little tighter than
some of you. I try to tighten just enough to stop the hood from being
loose and spinning around (which may be slightly more tight than the point
at which it just becomes secure from falling off).

Nevertheless, to me, a lens with this price tag, should be designed to handle this.
I'll be discussing with Canon service in more detail.

I don't know about you guys but I always leave the fibreglas tape on the inside of the clamp as it adds as a shim/buffer and also aids in avoiding marks made to the rubber hood trim from the bare clamp..

gpchase wrote:
I don't know about you guys but I always leave the fibreglas tape on the inside of the clamp as it adds as a shim/buffer and also aids in avoiding marks made to the rubber hood trim from the bare clamp..

gpchase wrote:
I don't know about you guys but I always leave the fibreglas tape on the inside of the clamp as it adds as a shim/buffer and also aids in avoiding marks made to the rubber hood trim from the bare clamp..PetKal wrote:
+1
Exactly....that is why Canon puts it there.

Glad you guys mentioned that. I haven't checked mine in a while. The gaffer's tape I use on my 200/1.8L hood lugs had worn through on all five of the lugs on that hood. The original fibreglass tape on my 500/4L IS hood was also worn through, and that on my 300/2.8L IS hood was completely gone. I upgraded all of them to Lee Valley duct tape. Finest kind!

jcolwell wrote:
Glad you guys mentioned that. I haven't checked mine in a while. The gaffer's tape I use on my 200/1.8L hood lugs had worn through on all five of the lugs on that hood. The original fibreglass tape on my 500/4L IS hood was also worn through, and that on my 300/2.8L IS hood was completely gone. I upgraded all of them to Lee Valley duct tape. Finest kind!

The front end of the lens barrel that contains the groove for securing the lens hood is made out of white painted metal in the Mark I lenses. Yes, after awhile the paint may be rubbed off and/or darkish (glue?) residues from tape are left in groove. The orange peal surface of the paint adds to the "filthy" appearance of the groove. The Mark II lenses have a black polycarbonate front piece instead and not only it shaves more weight, relative to that of the Mark I counterpart, but the darkish glue residues are not visible anymore and the polycarbonate piece is smoother than the painted surface.